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/*-*-c-*-*/
/*
* ufuncs to compute logit(p) = log(p/(1-p)) and
* expit(x) = 1/(1+exp(-x))
*/
#include <Python.h>
#include <math.h>
#include "numpy/npy_math.h"
#include "numpy/ndarraytypes.h"
#include "numpy/ufuncobject.h"
/*
* Inner loops for logit and expit
*/
/**begin repeat
* #type = npy_float, npy_double, npy_longdouble#
* #c = f,,l#
*/
static void
logit_loop@c@(char **args, npy_intp *dimensions,
npy_intp* steps, void* data)
{
npy_intp i;
npy_intp n = dimensions[0];
char *in = args[0], *out = args[1];
npy_intp in_step = steps[0], out_step = steps[1];
@type@ tmp;
for (i = 0; i < n; i++) {
tmp = *(@type@ *)in;
tmp /= 1 - tmp;
*((@type@ *)out) = npy_log@c@(tmp);
in += in_step;
out += out_step;
}
}
static void
expit_loop@c@(char **args, npy_intp *dimensions,
npy_intp* steps, void* data)
{
npy_intp i;
npy_intp n = dimensions[0];
char *in = args[0], *out = args[1];
npy_intp in_step = steps[0], out_step = steps[1];
@type@ tmp;
for (i = 0; i < n; i++) {
tmp = *(@type@ *)in;
if (tmp > 0) {
tmp = npy_exp@c@(tmp);
*((@type@ *)out) = tmp / (1 + tmp);
}
else{
*((@type@ *)out) = 1 / (1 + npy_exp@c@(-tmp));
}
in += in_step;
out += out_step;
}
}
/**end repeat**/
/*
* Definitions for the ufuncs.
*/
static PyUFuncGenericFunction expit_funcs[3] = {&expit_loopf,
&expit_loop,
&expit_loopl};
static PyUFuncGenericFunction logit_funcs[3] = {&logit_loopf,
&logit_loop,
&logit_loopl};
static char types[6] = {NPY_FLOAT, NPY_FLOAT,
NPY_DOUBLE, NPY_DOUBLE,
NPY_LONGDOUBLE, NPY_LONGDOUBLE};
static void *data[3] = {NULL, NULL, NULL};
/* Module definition */
static PyMethodDef module_methods[] = {
{ NULL, NULL, 0, NULL }
};
#if PY_VERSION_HEX >= 0x03000000
static PyModuleDef moduledef = {
PyModuleDef_HEAD_INIT,
"_logit",
NULL,
-1,
module_methods,
NULL,
NULL,
NULL,
NULL
};
PyMODINIT_FUNC
PyInit__logit()
{
PyObject *m, *f, *d;
m = PyModule_Create(&moduledef);
if (!m) {
return NULL;
}
import_array();
import_umath();
d = PyModule_GetDict(m);
f = PyUFunc_FromFuncAndData(logit_funcs,data, types, 3, 1, 1,
PyUFunc_None, "logit",NULL , 0);
PyDict_SetItemString(d, "logit", f);
Py_DECREF(f);
f = PyUFunc_FromFuncAndData(expit_funcs,data, types, 3, 1, 1,
PyUFunc_None, "expit",NULL , 0);
PyDict_SetItemString(d, "expit", f);
Py_DECREF(f);
return m;
}
#else
PyMODINIT_FUNC
init_logit()
{
PyObject *m, *f, *d;
m = Py_InitModule("_logit", module_methods);
if (m == NULL) {
return;
}
d = PyModule_GetDict(m);
import_array();
import_umath();
f = PyUFunc_FromFuncAndData(logit_funcs,data, types, 3, 1, 1,
PyUFunc_None, "logit",NULL , 0);
PyDict_SetItemString(d , "logit", f);
Py_DECREF(f);
f = PyUFunc_FromFuncAndData(expit_funcs,data, types, 3, 1, 1,
PyUFunc_None, "expit",NULL , 0);
PyDict_SetItemString(d , "expit", f);
Py_DECREF(f);
}
#endif
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